Revision 1.0

Page 17 of 44

nRF24AP2-USB Product Specification

Channel ID, search and pairing

The primary parameters which two ANT nodes use to identify each other make up the channel ID. Once

an ANT channel is established, the channel ID parameters must of course match; but they don’t have to

be known by both nodes (pre-configured) to be able to establish an ANT channel.

When an nRF24AP2 configured as a master (set in channel type) opens an ANT channel, it will broadcast

its entire channel ID. Hence you must configure all three channel ID parameters before opening an ANT

channel as a master.

On the other hand, in a slave you can configure nRF24AP2 to search for and connect with both known and

unknown masters. To connect with a known master you must configure the Transmission type, Device

type and Device number in nRF24AP2 before opening the ANT channel.

You can also configure the nRF24AP2 to conduct wild-card searches on one or more of the three parame-

ters in the channel ID to enable it to pair up with unknown masters. You can for instance set only the

Device type of the masters you want to link up with, and set wild cards on the Transmission type and

Device number. If a new master with a matching Device type is found, the slave device will connect and

store the unknown parts of the channel ID. The new parts of the channel ID can then be stored in the host

MCU to enable specific searches for this master later.

4.2.4

Proximity search

When using the basic search and pairing algorithm a slave will automatically identify and connect to the

first master it finds matching the search criteria. In areas where you either have a high density of similar

master nodes or high density of independent ANT networks, there is always the chance that multiple mas-

ters are found within the coverage area. This presents the risk that it is not the master you want to connect

to that is found first. The proximity search feature in ANT designates ‘bins’ of proximity from 1 (closest) to

10 (furthest) as shown in Figure 9. on page 17.

Figure 9. Standard search (a), Proximity search (b), showing bins 1-5 (of maximum 10)

This ‘binning’ enables you to further control your search, for example by only accepting the master that is

closest (only accepting masters that fall in bin 1-2). This makes it easy for a user to pair up network nodes

and prevent accidental connection to nodes possibly belonging to another network close by.